The objective of this project is to develop an emergency medical system (EMS) simulation model to be used in the planning of emergency medical services. The model is to be able to evaluate the effects on emergency medical services of changes in the following EMS factors: communications; emergency dispatching procedures; emergency vehicle routes; the number, location, and types of emergency facilities; treatment at the scene, enroute, and within the emergency facilites; number, types, and location of emergency vehicles; emergency vehicles equipment; and training of emergency vehicle attendants. The planning model is to have the capability to evaluate changes in the EMS factors in terms of appropriate measures of effectiveness such as emergency system response time, emergency victims mortality rates, and the percentage utilization of emergency system components. Also, the incidence of long delays before the arrival of an emergency vehicle is to be incorporated in the model as a measure of effectiveness. The EMS planning model may be used by health planners who must determine how best to change an emergency medical system to respond to the expanding demands for emergency services or to improve the performance of an emergency medical system.